You can keep an automatic mechanical watch running just by moving around, but you don’t have that luxury with smartwatches — at some point, you have to take them off to recharge the battery. That may not be an issue in the future, however. As the South China Morning Post reports, researchers at the Chinese University of Hong Kong have developed technology (pictured below) that would keep smartwatches powered by human movement.

The breakthrough revolves around an energy harvester with a magnetic frequency converter that amplifies the output by “ten times” to 1.74mW. Swing your arm and you could have enough power from that movement to drive a smartwatch display, processor and health tracking features like a heart rate sensor. The amount of power would depend on your activity (a workout would be far better than sitting at your desk), but you might never need to take the watch off your wrist if it’s efficient enough.